Projection system

ABSTRACT

A photographic system for projection of images on a continuous flow basis between a medium carrying images and a medium being exposed to them and providing for adjustable magnification or reduction of images and wherein the speed or travel of the viewed and exposed media are precisely determined and synchronized in accordance with the speed of one of them and the ratio of image magnification or reduction.

United States Patent Inventors Doyle W. Thomas;

Clarence E. Ellis, both of Huntsville, Ala. Appl. No. 788,378 Filed Jan. 2, 1969 Patented Aug. 10, 1971 Assignee Space, Inc.

Huntsville, Ala.

PROJECT [ON SYSTEM 15 Claims, 11 Drawing Figs.

0.8. CI 355/51, 318/69, 318/77, 355/57, 355/60, 355/66 Int. Cl G03b 27/70 Field of Search 355/51,

[56] References Cited UNITED STATES PATENTS 2,903,941 9/1959 Bornemann 355/42 3,225,649 12/1965 Timares et al. 355/42 3,507,576 4/1970 Linde 355/65 X Primary Examiner-Samuel S. Matthews Assistant ExaminerRichard A. Wintercorn Attorney-C. A. Phillips ABSTRACT: A photographic system for projection of images on a continuous flow basis between a medium carrying images and a medium being exposed to them and providing for adjustable magnification or reduction of images and wherein the speed or travel of the viewed and exposed media are precisely determined and synchronized in accordance with the speed of one of them and the ratio ofimage magnification or reduction.

IO 25 a" 53 1 87 so 36/ 36 52 so l2 I N MAGNIHCATION RATIO PATENTED Am; I 0 an SHEET 1 OF 5 FIG. I

|b2bsb4o5osb7bab9b|do 0F TRAVEL OF MIRROR ASSEMBLY FIG. 2

Doyie W. Thomas Clarence E. Ellis,

INVENTORS.

ORNEY FILM DRIVE INVERTING SHEET 2 BF 5 POWER AMPLIFIER ANALOG MULTIPLIER m 4 r I I 5 1 4:4 Lu J? 4 a. Y e L a m l n j u P M H: m w on k L .9 1 i1 Fkh L CLOCKWISE PA TENTED AUG 1 0 m SUMMING AMP YFIG.6

I-L F: I 5 I g l 5 1 I I PATENTEIIAUBI 019?:

SHEET 3 UF 5 FIG.7

Doyle W. Thomas Clarence E Elhs,

INVENTORS BY ZTT NEY GUIDE BAR E \LPUSH TO RELEASE FIG. 5

PATENIED Am: I man SHEEI 5 OF 5 Doyle W. Thomas Clarence E. Ellis,

INVENTORS.

BY ZT T ORNFY PROJECTION SYSTEM This invention relates to photographic projection and printing of material on a continuous flow basis, as for example where images initially appearing on a long strip of paper or film are to be enlarged or reduced on photographic media, paper or film.

The photographic printing of material on a continuous flow basis generally involves two basic problems.

One is the problem of providing in a practical and economical manner apparatus for varying the degree of magnification or reduction of the image size between the paper or film carrying the image and the paper or film to which the image is to be transferred over a sufficient range of magnification or reduction. Ideally, the range would cover from 7 times to 24 times magnification or reduction continuously and by a single range adjustment.

Second is the problem of precisely regulating the movement or travel of the paper or film being viewed and the paper or film being exposed in accordance with the ratio of magnification or reduction in image size.

Accordingly, it is an object of this invention to overcome these and other problems and difficulties and to provide a projection system and printer which will accurately, conveniently and with minimum cost print on paper or film images which are an enlarged or reduced facsimile of an original and which permits the continuous printing of a series of distinct images or pictures or other intelligence or data of varying lengths.

It is another object of this invention to provide an optical system for the enlargement or reduction of projected images without the necessity of relative movement of the focal planes between which magnification or reduction of images is desired, and without the necessity of multifocal length lens assemblies.

It is still a further object of this invention to provide a system of maintaining precise relative speeds between a pair of transport systems which transport long strips of paper or other material.

In accordance with the invention, the general and specific objects of this invention are achieved by a combination of the following features: 1

First, variable magnification or reduction is achieved by interrupting the optical path between the viewed media and media being exposed and interjecting anoptical system for varying optical path lengths by changing the position of at least one mirror with respect to other optical elements of the system. As a particular feature of this invention the optical system consists of two sets of mirror assemblies in which the first mirror assembly consists of two plane mirrors with surfaces disposed in planes which are displaced 270 and the second mirror assembly consists of two plane mirrors wherein the two surfaces of the mirrors are disposed in planes which are 90 displaced. The two mirror assemblies are positioned in optical alignment wherein an image directed at a first mirror of the first mirror assembly is reflected to the first mirror of the second mirror assembly, again reflected to the second mirror of the second mirror assembly, then reflected along a generally parallel path to the second mirror of the first mirror assembly by which mirror the image is reflected on an optical path leading to the focal plane where it is to be viewed or to expose a photosensitive medium. Ten by incorporating means for varying the distance between at least two mirrors the overall optical path length between focal planes is variable v and thus the degree of magnification or reduction is variable. Where only a small portion of width of an image is being projected, which is constant, the mirror widths of the mirrors of the mirror system may be made small. The mirror lengths vary with the size image appearing at the point of placement of a mirror. By width is meant the dimension which corresponds to the slit width of the viewing aperture, that is the aperture which exposes the photographic medium.

In order to maintain the dimensional accuracy of reproduction, precise control of speed of the medium carrying the images being viewed and the medium being exposed must be maintained at a ratio of speeds which is equal to the ratio of image'sizes appearing at the apertures. To accomplish this, one of the two drive systems employed is driven at a selected speed. The other drive system is electrically controlled in speed by means of an electrical input which is a selected fraction of an electrical signal proportional to the speed of the first drive system. The selected fraction, of course, is equal to the fraction of the reduction, or ratio, between the images.

Other objects, features and advantages of the invention will become more apparent from the following description when read in connection with the accompanying drawings in which:

FIG. 1 is a schematic illustration of the system of the invention.

FIG. 2 is a graph on which is plotted the relationship between percentage of travel of a mirror assembly as shown in FIG. I with respect to the magnification ratio of the system.

FIG. 3 is a block diagram and alternate system for controlling the speed of the film drive motor shown in FIG. 1.

FIG. 4 is a side view, partly diagrammatic, illustrating the mirror system of the invention.

FIG. 5 is a detailed drawing illustrating the method of mounting of a microswitch or lever operated plunger switch shown in FIG. 4.

FIG. 6 is a schematic illustration of the electrical drive system which adjusts magnification ratio.

FIG. 7 is a side view of the photographic paper magazine shown partially in FIG. 11.

FIG. 8 is an elevation view of the arrangement of major components of an embodiment invention.

FIG. 9 is a plan view of a film projection portion of the invention as illustrated in FIG. 8.

FIG. 10 is a pictorial view of the exterior of one form of the invention.

FIG. 11 is an exploded view of FIG. 10.

Referring now to FIG. 1, there is shown a system for transferring images between focal planes I0 and 12. In this embodiment of the invention, it is contemplated that the photographic medium I4 would be in the form of a long strip of unexposed photographic paper, or alternately, paper with printed images. In either instance it would initially be wound on storage reel 16. The paper would then be drawn by and wound on takeup reel 18 while being positioned within focal plane 10 between aperture plates 20. Takeup reel 18 is driven through an appropriate gearing system 22 by motor 24, which also drives paper 14 at a desired constant speed through capstan 25. Motor 24 is controlled by speed control system 26 in which a desired speed is set by means of a selected voltage obtained from potentiometer 28 which is applied to amplifier 30, which in turn drives motor 24. Tachometer 31 which is driven by motor 24, develops a voltage proportional to the speed of motor 24, and this voltage is applied as negative feedback input to amplifier 30 to insure that the speed of motor 24 is driven at the selected speed despite variations in load on motor 24.

The image at focal plane 12 may be an image printed on film 32, or an image received on an unexposed film 32 from an image appearing on photographic paper 14, depending upon the mode of operation. In either of the modes, the film is originally stored on reel 38, and then passes between aperture plates 36 and is reeled or spooled on takeup reel 34. The speed of film 32 across aperture slit 40 is precisely synchronized with the movement of paper I4 across aperture slit 42. As a particular feature of this invention, this is accomplished by film speed control system 44 which derives a reference voltage from potentiometer 46 and applies it to amplifier 48 which powers motor 50. Motor 50 drives capstan 49 through reduction gear 52 which drives film 32 and takeup reel 34. The voltage across potentiometer 46, derived from tachometer 31, is proportional to the speed of motor 24, and thus by selecting a voltage output which is that fraction of the total voltage corresponding to the desired speed of motor 50, a precise control of motor 50 can be obtained which corresponds to the desired ratio of reduction of image sizes betweenfocal plane and focal plane 12. Tachometer 54 provides the desired negative feedback voltage to amplifier 48 to achieve accurate regulation of motor 50.

As another feature of this invention, speed selection is achieved by movement of wiper arm 55 of potentiometer 46 in a manner to be described below.

Typically, the width of paper 14 would be substantially larger than film 32, the latter being, typically, 35 millimeter film. Image reduction or magnification, depending upon whether the image is initially on the paper or film, is achieved by mirror assemblies 54 and 56. An image, for example, on film 32 is projected by means of light source 58 to movable mirror 60, is reflected 90 to the side and then by mirror 115 (FIG. 9) is reflected 90 up through projection lens assembly 62 on to mirror face 64 of mirror assembly 54. From mirror face 64 it is reflected to mirror face 66 of mirror assembly 56, then to mirror face 68, then on to mirror face 69 of mirror assembly 54 and then on to paper 14. Mirror faces 64, 66, 68 and 69 are progressively of longer lengths in order to accommodate the progressively larger image which occurs.

As still another feature of this invention, mirror assemblies 54 and 56 are relatively movable to vary the distance between them and in this manner it is possible to vary the ratio of magnification, or reduction of images with a single projection lens assembly 62. This is accomplished by means, of motor 70 which, as directed by motor control 71, and through drive means 72, illustrated in FIG. 4, moves mirror assembly 56 toward or away from mirror assembly 54. In varying the optical path length of the system, motor 70 also controls through drive means 72 wiper arm 55 of potentiometer 46 and thus by means of motor control 71 both the image ratio and speed ratio of the film and paper drives are precisely set by one operation.

Where the initial image is on paper 14, and is to be photographed on film 32, the image on paper 14 is illuminated by lights 73 and the image travels in the reverse direction to that just described and on to film 32. When the image is originally on paper 14, it is projected on to mirror 69, then to mirror 68, then to mirror 66, then to mirror 64, through projection lens 62, on to mirrors 104 and 60 and then on to film 32. To observe focusing of the image, mirror 60 is reversed (dashed line position in FIG. 9) to that of the position indicated in FIG. 1 and images are'reflected out to ground glass 74, ground glass 74 being the same distance from the mirror 60 as the focal plane of film 32. In addition, the actual image size appears on ground glass 74 and thus, image size can be observed for adjustment in the same manner. Similarly, in instances where the image is initially on film 32 and is projected upward to paper 14, by moving mirror 69 (dashed line position in FIG. 4) from the optical .path the image is projected on to ground glass 76 where it can be viewed and mirror assembly 56 and lens assembly 62, manually or by means of motor 70, adjusted to achieve precise image size and focus. Ground glass 76 is, of course, the same distance from mirror 69 as is the focal plane in which paper 14 travels.

The magnification ratio of the system is determined as described above by increasing or decreasing the path length between film and paper which is accomplished by varying the distance between mirror assemblies 54 and 56. The magnification ratio can be derived from the following standard equation:

Where F is the focal length of lens 62, P is the distance between one image source and lens or lens assembly 62, and Q is the distance between the other image source and lens 62.

The magnification ratio is given by the ratio of P to Q, whereas the optical path distance is given by P+Q. Solving for the magnification ratio m in terms of optical path distance results in a relationship between these two variables as shown in the following table:

The data in this table was prepared for a 35 mm. lens for magnification ratios between 7' to l and 24 to I. This data is plotted in FIG. 2, however the optical path length P-l-Q is replaced with a percent of travel of mirror assembly 56. This latter variable is, of course, equivalent to an electrical signal that may be derived from the movement of mirror assembly 56. The relationship can be seen to be very linear between the ratios of 10 to l and 24 to 1. Within this range 'a voltage derived from movement of mirror assembly 56 is directly proportional to the desired magnification ratio. In smaller ratios it is necessary to make corrections for the nonlinearity, which can be simply built into the system. For example, in developing an appropriate electrical signal representative of magnification ratio, potentiometer 46 would be appropriately wound to compensate for the nonlinearity illustrated in FIG. 2.'

FIG. 3 illustrates an alternate electrical circuit for synchronizing paper and film speeds. This circuit functions to synchronize the speed of paper 14 and film 32 by maintaining the magnification ratio, as determined by the optical system, equal to v,,/ v,, the ratio of the velocity of paper 14 with respect to film 32. The optical magnification ratio m is obtained in the form of voltage from potentiometer 46 and is applied as one input to summing amplifier 80. In this circuit potentiometer 46 is powered by a fixed reference potential instead of an output of tachometer 31 as shown in FIG. 1. Also applied to summing amplifier 80 is a voltage proportional to v,,v, as derived from actual speeds of paper 14 and film 32 as will be described below. The output of summing amplifier 80 is then fed to power amplifier 82 and then to motor 50 which in turn drives film drive 52 which drives film 32. Tachometer 54 is driven by motor 50 and provides an electrical signal proportional to the speed of motor 50, which signal, v,, is inverted by inverting amplifier 84 to produce a voltage proportional to the inverse of film speed, l/v,. This signal is then multiplied in multiplier 86 by a voltage proportional to the paper speed, v, derived from tachometer 31 which is then fed to summing amplifier 80 as a signal v,,/v,. Thus, the system functions by providing an input to power amplifier 82 which includes an error signal, which is the difference between m and v,,/v, causing motor 50 to be driven at such speed as will correct any error and thus drive the speed ratio of v,,/v,in to coincidence with the magnification ratio m.

Referring to FIG. 4, depending upon direction of rotation of worm gear 90, mirror mount or mounting assembly 92 moves mirror assembly 56 closer to or further away from mirror assembly 54. At the same time, support 96 attached to mirror mount 94 also moves wiper 55 of potentiometer 46 to provide an output voltage which is representative of the ratio of magnification of the system of FIG. 3 (or selected fraction of paper speed per FIG. 1) as adjusted by the distance between mirror assemblies 54 and 56.

The magnification setting of mirror mount 92 may be achieved by means of prepositioned stops or microswitches 104 or by viewing the projected image on ground glass 76 or 60 and causing motor 70 to be operated in the direction which brings the image to desired size.

REferring to FIGS. 4-6 there is shown a system of control for motor 70. A source of 110 volt AC is applied to terminals 105 of motor control 71 and applied through a direction selector switch, a normally open double'throw, triple-pole switch 106 to reference winding 107 of motor 70 and through normally closed selector switches 108 and normally closed lever operated or microswitches 104, in parallel, to winding 109 of motor 70.

Microswitches a to d of microswitches 104 are adjustably movable on guide bar 110 being held by spring mounts 111. These switches are positioned to be operated open" by a pawl 112 on mirror mount 92 at positions corresponding to preselected magnification ratios.

In operation, assure first that a purely visual method is to be used to determine the image to be projected on paper 14 from film 32. Mirror 69 is moved down to horizontal position and out of the way to permit the projected image to be projected on ground glass 76. Then, depending upon whether the image is to be made larger or smaller, switch 106 is operated for clockwise or counterclockwise operation of motor 70. In this general mode of operation all panel selector switches 1113 are left in their normally closed position and power is supplied to motor 70 until the desired image size is observed, whereupon the operator would open switch 106.

If one of the preset ratios is desired then the particular selector switch 108 is operated which is electrically in parallel with the particular microswitch 104 which is positioned for cutoff at the desired ratio. Assuming, for example, that it is the ratio represented by microswitch 104C, thus panel switch 108C would be operated open. Next, switch 106 would be operated on, either clockwise or counterclockwise, as required, to cause mirror mount 92 to move until it actuates switch 104C which removes power from motor 70 and mirror assembly is stopped and positioned for the selected image size.

'It is, of course, necessary each time that there is a change in magnification ratio that lens 62 be refocused. Accordingly, as another feature of this invention, and as shown in FIG. 1, motor drive 72 and mirror assembly 56 are also connected through appropriate drive means, not shown, to lens 62 whereby the barrel of lens 62 is rotated in a conventional manner to adjust lens 62 to follow and maintain focus of the system in accordance with the optical path length between the focal planes of paper 14 and film 32. Alternately, lens 62 can be independently focused by disconnecting it from drive 72. While not shown, switch-operating means may be included to automatically reverse switch 106 at each end of travel of mirror mount 92 (FIG. 6) so that mirror mount 92 will be moved to a cutoff position regardless of which way switch 98 is initially operated.

Referring now to FIGS. 8 and 9 and assuming that images on film 32 are to be projected and exposed on paper 14, light source 58 is turned on. Bulb 113 projects lights through condenser lens assembly 114 and through film 32. Images on film 32 are then directed from aperture 36 to mirror 60 which reflects the images to the left to mirror 115 which reflects the images, this time upward, to lens 62. Lens 62 then projects the images through mirror assembly 54 and 56 up through aperture 42 and slit 118 of paper magazine 1211 (FIG. 7) and on to paper 14. Paper 14, initially on supply reel 16, passes under capstan 25 and between capstan 25 and belt 124, then between belts 124 and 126, to reel 18. Belts 124 and 126 are each of at least the width of paper 14 and as paper 14 passes between these belts it is flattened so that it will be positioned in a plane when passing slit 118 which is aligned with focal plane 42. Slit 118 is adjustable in width and by means of slide holder 130 and it may be closed to prevent light from entering when magazine 120 is not in use, and when containing sensitized paper.

Belt 124 is supported by rollers 132, 134 and 136 and paper 14 is fed between capstan 25 and belt 124 at a precise speed as determined by capstan 25. Belt 126 is an idler belt and is supported byrollers 138 and 140. Takeup reel 18 is driven by means of belt 142 and frictional drive 144 and braking torque is applied to reel 16 by means of belt 146 and frictional coupling 148.

Referring again to film 32 and FIGS. 8 and 9, film 32 is driven by capstan 49 as it passes between it and pinch roller 150. In unwinding from reel 34 and winding on reel 38, film 32 also passes between guide rollers 154 and over guide rollers I 156. Belts I58 and 1611 provide a frictional drive torque to reel 38 through friction drive 162 and a drag torque to reel 34 through frictional coupling 164. Thus, the film is positively driven at a precise speed by means of capstan 49 from drive motor 50 including reduction gears shown diagrammatically in FIG. I and a drive tension is applied to takeup reel 38 and a drag tension applied to supply reel 34.

FIG. 10 generally shows the housing of the system heretofore described. It consists of main assembly cabinet 170 and removable paper magazine 1211.

FIG. 11 shows pictorially rack 172, on which the basic as sembly is mounted, cabinet 170 and paper magazine 120. By making paper magazine detachable, different size paper may be employed by merely substituting magazines having the desired paper size. Motor drive 174 for paper 14 is also located in housing 176 (FIGS. 8 and 11) and is coupled to capstan 25 by means of a shaft 176 and coupling 178 in a manner, not shown, wherein the drive is quickly disconnected by simply lifting magazine 120.

From the foregoing, it will be understood that the applicants have provided a new system of projection on a continuous basis between film 32 and paper 14 which are moved at a relative speed precisely set and automatically maintained.

What we claim is:

1. A projection system for projecting images between first and second focal planes comprising:

A. Lens means responsive to an image appearing at a predetermined location in one of said focal planes for projecting said image in the other said focal plane at a predetermined location;

B. A plurality of mirrors spaced along and providing an optical path between said images comprising:

1. a first mirror positioned to receive images from and transmit images to one of said focal planes;

2. a second mirror positioned to receive images from and transmit images to the other of said focal planes; and

3. third and fourth mirrors, said third mirror being positioned to transmit images between said fourth mirror and said first mirror and said fourth mirror being positioned to transmit and receive images between said third mirror and said second mirror; and

C. Image size adjustment means comprising positioning means attached to at least one of said mirrors for varying the path length between the images whereby the relative size of said images is varied without varying the said locations.

2. A projection system comprising:

A. A first rectangular aperture having a length substantially longer than its width;

B. A first reeling system for moving a first elongated sheet of image material across and adjacent to said aperture wherein the width dimension of said material is oriented to be exposed to the length dimension of said aperture;

C. A second rectangular aperture having a length substantially longer than its width and being smaller in both dimensions than said first aperture;

D. A second reeling system for moving a second elongated sheet of image material across and adjacent to said second aperture wherein the width dimension of said second elongated sheet ofimage material is oriented to be exposed to the length dimension ofsaid second aperture;

E. Projection means for projecting an image appearing in a focal plane of one of said sheets of material at a said aperture on to the focal plane of the other of said sheets of image material at the other said aperture;

F. Image size adjustment means comprising means for continuously varying the optical path length between a said image and its projected image;

G. First electrical drive means for driving said first reeling system to cause'said image material to traverse said first aperture at a selected speed;

H. Second electrical drive means for driving said second reeling system to cause said image material to traverse said second aperture at a selected but continuously variable speed;

I. First speed control means for regulating the speed of said first electrical drive means; and

J. Second speed control means responsive to the speed of said first electrical drive means and the ratio of the size of a said image in one said focal plane and its projection in the other said focal plane for regulating the speed of the said second electrical drive means.

3. A projection system as set forth in claim 2 wherein:

A. Said second electrical drive means comprises an electrical 'motor coupled to drive said second reeling system;

B. Speed-sensing means responsive to the speed of said first electrical drive means for providing an electrical signal proportional to the speed of said first electrical drive means;

C. Said second speed control means comprising means responsive to output of said speed-sensing means for applying as on input to said second electrical drive means the fraction of the output of said speed-sensing means corresponding to the said ratio of the sizes of said images.

4. A projection system as set forth in claim 2 wherein said image size adjustment means comprises:

A. A plurality of mirrors spaced along and providing an optical path between the images appearing in the said focal planes; and

B. Said image size adjustment means comprises positioning means attached to at least one of said mirrors for varying the path length between the images whereby the relative size of said image is varied without varying the location of either a said image in one said focal plane or its projected image in the other said focal plane.

5. The projection system set forth in claim 4 wherein said plurality of mirrors comprises:

A. A first mirror positioned to receive images from and transmit images to one of said focal planes;

B. A second mirror positioned to receive images from and transmit images to the other of said focal planes; and

C. Third and fourth mirrors, said third mirror being positioned to transmit images between said fourth mirror and said first mirror and said fourth mirror being positioned to transmit and receive images between said third mirror I and said second mirror.

6. A projection system as set forth in claim 5 wherein said image size adjustment means comprises means for selectively varying the distance of said third and fourth mirrors from said first and second mirrors.

7. A projection system as set forth in claim 6 wherein the optical path between said first and third mirrors and optical path between said second and fourth mirrors are parallel and wherein said image size adjustment means comprises means for moving said third and fourth mirrors in unison along a linear path.

8. A projection system as set forth in claim 2 wherein said image size adjustment means comprises:

A. A first mirror positioned to receive images from and transmit images to one of said focal planes;

B. A second mirror positioned to receive images from and transmit images to the other of said focal planes;

C. Third and fourth mirrors, said third mirror being positioned to transmit images between said fourth mirror and F. Summing means for electrically adding the output of said ratio signal means and an electrical signal proportional to the ratio of speed of said first and second drive means and applying the sum signal to said second drive means;

G. First speed-sensing means responsive to the speed of said second drive means for developing an electrical output proportional to the reciprocal of said speed of said second drive means;

l-l. Second speed-sensing means responsive to the speed of said first drive means for developing an electrical output proportional to the speed of said first drive means; and

l. Electrical multiplication means responsive to the outputs of said first and second speed-sensing means for providing to said summing amplifier said electrical signal proportional to the said ratio of speeds of said first and second drive means.

9. A projection system as set forth in claim 8 wherein said image size adjustment means comprises:

A. Mounting means for movably supporting said third and fourth mirrors; and

B. Mirror drive means including a reversible motor and a clockwise-counterclockwise switch for providing power to said reversible motor, said motor being coupled to said mirror mounting means for selectively moving said third and fourth mirrors along said linear path to increase or decrease the distance of said third and fourth mirrors with respect to said first and second mirrors.

10. A projection system as set forth in claim 9 wherein said mirror drive means further comprises a selective stop circuit in circuit between said clockwise-counterclockwise switch and said reversible motor comprising:

A. A plurality of normally closed selector switches connected in series;

B. A plurality of normally closed position-sensing switches being positioned to be operated off by said mirror mounting means contacting a said position-sensing switch, said position-sensing switches being spaced along the travel of said mirror-mounting means; and

C. Each said selector switch being connected in parallel with a single said position-sensing switch whereby when said clockwise-counterclockwise switch is operated to an on condition said mirror-mounting means will be moved along its path of travel until the position responsive switch in parallel with an operated of said selector switch is also operated of stopping the travel of said mirror-mounting means. i

11. A projection system as set forth in claim 10 further comprising means for selectively positioning said position-sensing switches whereby said third and fourth mirrors may be stopped at any of a plurality of preselected points along the travel of said mirror mounting means.

12. A projection system as set forth in claim 11 wherein said ratio signal means comprises a potentiometer wherein the wiper arm of the potentiometer is coupled for travel with said mirror-mounting means.

13. A projection system as set forth in claim 12 further comprising means responsive to movement of said mirror-mounting means for varying the focus of said lens means for maintaining the focus of said images.

14. In combination:

A. A first reeling system for moving a first elongated sheet of material;

B. A second reeling system for moving a second elongated sheet of material;

C. First electrical drive means for driving said first reeling system at a selected speed;

D. Second electrical drive means for driving said second reeling system at a selected but continuously variable speed which is a desired fraction of the speed of said first electrical drive means comprising a motor coupled to drive said second reeling system;

E. Speed-sensing means responsive to the speed of said first electrical drive means for providing an electrical signal proportional to the speed of said first electrical drive means; and

F. Speed control means comprising means responsive to the output of said speed-sensing means for applying as on input to said motor the fraction of the output of said speed-sensing means corresponding to the desired ratio of speed synchronism between said first and second electrical reeling systems.

15. In combination:

A. First and second electrical drive means adapted to provide movements at different speeds,

B. Ratio signal means for providing an electrical output proportional to the desired ratio of speeds between first and second electrically driven movements;

C. Summing means for electrically adding the output of said ratio signal means and an electrical signal proportional to the ratio of the actual speeds of said first and second drive means and applying the sum signal to said second electrical drive means;

D. First speed-sensing means responsive to the speed of said second electrical drive means for developing an electrical output proportional to the reciprocal of said speed of said second electrical drive means;

E. Second speed-sensing means responsive to the speed of said first electrical drive means for developing an electrical output proportional to the speed of said first electrical drive means; and

F. Electrical multiplication means responsive to the outputs of said first and second speed-sensing means for providing to said summing means said electrical signal proportional to the said ratio of speeds of said first and second electrical drive means. 

1. A projection system for projecting images between first and second focal planes comprising: A. Lens means responsive to an image appearing at a predetermined location in one of said focal planes for projecting said image in the other said focal plane at a predetermined location; B. A plurality of mirrors spaced along and providing an optical path between said images comprising:
 1. a first mirror positioned to receive images from and transmit images to one of said focal planes;
 2. a second mirror positioned to receive images from and transmit images to the other of said focaL planes; and
 3. third and fourth mirrors, said third mirror being positioned to transmit images between said fourth mirror and said first mirror and said fourth mirror being positioned to transmit and receive images between said third mirror and said second mirror; and C. Image size adjustment means comprising positioning means attached to at least one of said mirrors for varying the path length between the images whereby the relative size of said images is varied without varying the said locations.
 2. a second mirror positioned to receive images from and transmit images to the other of said focaL planes; and
 2. A projection system comprising: A. A first rectangular aperture having a length substantially longer than its width; B. A first reeling system for moving a first elongated sheet of image material across and adjacent to said aperture wherein the width dimension of said material is oriented to be exposed to the length dimension of said aperture; C. A second rectangular aperture having a length substantially longer than its width and being smaller in both dimensions than said first aperture; D. A second reeling system for moving a second elongated sheet of image material across and adjacent to said second aperture wherein the width dimension of said second elongated sheet of image material is oriented to be exposed to the length dimension of said second aperture; E. Projection means for projecting an image appearing in a focal plane of one of said sheets of material at a said aperture on to the focal plane of the other of said sheets of image material at the other said aperture; F. Image size adjustment means comprising means for continuously varying the optical path length between a said image and its projected image; G. First electrical drive means for driving said first reeling system to cause said image material to traverse said first aperture at a selected speed; H. Second electrical drive means for driving said second reeling system to cause said image material to traverse said second aperture at a selected but continuously variable speed; I. First speed control means for regulating the speed of said first electrical drive means; and J. Second speed control means responsive to the speed of said first electrical drive means and the ratio of the size of a said image in one said focal plane and its projection in the other said focal plane for regulating the speed of the said second electrical drive means.
 3. A projection system as set forth in claim 2 wherein: A. Said second electrical drive means comprises an electrical motor coupled to drive said second reeling system; B. Speed-sensing means responsive to the speed of said first electrical drive means for providing an electrical signal proportional to the speed of said first electrical drive means; C. Said second speed control means comprising means responsive to output of said speed-sensing means for applying as on input to said second electrical drive means the fraction of the output of said speed-sensing means corresponding to the said ratio of the sizes of said images.
 3. third and fourth mirrors, said third mirror being positioned to transmit images between said fourth mirror and said first mirror and said fourth mirror being positioned to transmit and receive images between said third mirror and said second mirror; and C. Image size adjustment means comprising positioning means attached to at least one of said mirrors for varying the path length between the images whereby the relative size of said images is varied without varying the said locations.
 4. A projection system as set forth in claim 2 wherein said image size adjustment means comprises: A. A plurality of mirrors spaced along and providing an optical path between the images appearing in the said focal planes; and B. Said image size adjustment means comprises positioning means attached to at least one of said mirrors for varying the path length between the images whereby the relative size of said image is varied without varying the location of either a said image in one said focal plane or its projected image in the other said focal plane.
 5. The projection system set forth in claim 4 wherein said plurality of mirrors comprises: A. A first mirror positioned to receive images from and transmit images to one of said focal planes; B. A second mirror positioned to receive images from and transmit images to the other of said focal planes; and C. Third and fourth mirrors, said third mirroR being positioned to transmit images between said fourth mirror and said first mirror and said fourth mirror being positioned to transmit and receive images between said third mirror and said second mirror.
 6. A projection system as set forth in claim 5 wherein said image size adjustment means comprises means for selectively varying the distance of said third and fourth mirrors from said first and second mirrors.
 7. A projection system as set forth in claim 6 wherein the optical path between said first and third mirrors and optical path between said second and fourth mirrors are parallel and wherein said image size adjustment means comprises means for moving said third and fourth mirrors in unison along a linear path.
 8. A projection system as set forth in claim 2 wherein said image size adjustment means comprises: A. A first mirror positioned to receive images from and transmit images to one of said focal planes; B. A second mirror positioned to receive images from and transmit images to the other of said focal planes; C. Third and fourth mirrors, said third mirror being positioned to transmit images between said fourth mirror and said first mirror and said fourth mirror being positioned to transmit and receive images between said third mirror and said second mirror. D. Adjustment means for selectively varying the distance of said third and fourth mirrors from said first and second mirrors. E. Ratio signal means responsive to the position of third and fourth mirrors for providing and electrical output proportional to the ratio of magnification between said images. F. Summing means for electrically adding the output of said ratio signal means and an electrical signal proportional to the ratio of speed of said first and second drive means and applying the sum signal to said second drive means; G. First speed-sensing means responsive to the speed of said second drive means for developing an electrical output proportional to the reciprocal of said speed of said second drive means; H. Second speed-sensing means responsive to the speed of said first drive means for developing an electrical output proportional to the speed of said first drive means; and I. Electrical multiplication means responsive to the outputs of said first and second speed-sensing means for providing to said summing amplifier said electrical signal proportional to the said ratio of speeds of said first and second drive means.
 9. A projection system as set forth in claim 8 wherein said image size adjustment means comprises: A. Mounting means for movably supporting said third and fourth mirrors; and B. Mirror drive means including a reversible motor and a clockwise-counterclockwise switch for providing power to said reversible motor, said motor being coupled to said mirror mounting means for selectively moving said third and fourth mirrors along said linear path to increase or decrease the distance of said third and fourth mirrors with respect to said first and second mirrors.
 10. A projection system as set forth in claim 9 wherein said mirror drive means further comprises a selective stop circuit in circuit between said clockwise-counterclockwise switch and said reversible motor comprising: A. A plurality of normally closed selector switches connected in series; B. A plurality of normally closed position-sensing switches being positioned to be operated ''''off'''' by said mirror-mounting means contacting a said position-sensing switch, said position-sensing switches being spaced along the travel of said mirror-mounting means; and C. Each said selector switch being connected in parallel with a single said position-sensing switch whereby when said clockwise-counterclockwise switch is operated to an ''''on'''' condition said mirror-mounting means will be moved along its path of travel until the position responsive switch in parallel with an operated ''''off'''' said selector switch Is also operated ''''off'''', stopping the travel of said mirror-mounting means.
 11. A projection system as set forth in claim 10 further comprising means for selectively positioning said position-sensing switches whereby said third and fourth mirrors may be stopped at any of a plurality of preselected points along the travel of said mirror mounting means.
 12. A projection system as set forth in claim 11 wherein said ratio signal means comprises a potentiometer wherein the wiper arm of the potentiometer is coupled for travel with said mirror-mounting means.
 13. A projection system as set forth in claim 12 further comprising means responsive to movement of said mirror-mounting means for varying the focus of said lens means for maintaining the focus of said images.
 14. In combination: A. A first reeling system for moving a first elongated sheet of material; B. A second reeling system for moving a second elongated sheet of material; C. First electrical drive means for driving said first reeling system at a selected speed; D. Second electrical drive means for driving said second reeling system at a selected but continuously variable speed which is a desired fraction of the speed of said first electrical drive means comprising a motor coupled to drive said second reeling system; E. Speed-sensing means responsive to the speed of said first electrically drive means for providing an electrical signal proportional to the speed of said first electrical drive means; and F. Speed control means comprising means responsive to the output of said speed-sensing means for applying as on input to said motor the fraction of the output of said speed-sensing means corresponding to the desired ratio of speed synchronism between said first and second electrical reeling systems.
 15. In combination: A. First and second electrical drive means adapted to provide movements at different speeds, B. Ratio signal means for providing an electrical output proportional to the desired ratio of speeds between first and second electrically driven movements; C. Summing means for electrically adding the output of said ratio signal means and an electrical signal proportional to the ratio of the actual speeds of said first and second drive means and applying the sum signal to said second electrical drive means; D. First speed-sensing means responsive to the speed of said second electrical drive means for developing an electrical output proportional to the reciprocal of said speed of said second electrical drive means; E. Second speed-sensing means responsive to the speed of said first electrical drive means for developing an electrical output proportional to the speed of said first electrical drive means; and F. Electrical multiplication means responsive to the outputs of said first and second speed-sensing means for providing to said summing means said electrical signal proportional to the said ratio of speeds of said first and second electrical drive means. 